JP2007081128A - Superconductive coil and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductive coil which is constituted by a compound superconductive wire in which an internal distortion is relaxed and can improve superconductive properties such as a distortion resistance property and a critical current value than before, and to provide a method of manufacturing the superconductive coil. <P>SOLUTION: The superconductive coil is formed by winding the compound superconductive wire in which a superconductive formation heat treatment is performed. The compound superconductive wire has a compound superconductor in at least a part of an interior of a cross section thereof, and after a predetermined compound superconductor formation heat treatment is performed, the internal distortion of the compound superconductive wire is relaxed by carrying out both vibrating and bending processes in which a bending distortion is added from both directions, that is, a forward direction and a backward direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a superconducting coil by a react and wind method using a compound superconducting wire and a manufacturing method thereof, and more particularly to a superconducting coil having a large excitation current and a low manufacturing cost and a manufacturing method thereof.

Conventionally, as a method of manufacturing a superconducting coil composed of a compound superconducting wire or cable using a compound superconductor such as Nb ₃ Sn superconducting, compound superconducting, which is a heat treatment for generating a compound superconductor on a wire containing a compound superconducting raw material inside A so-called “react and wind” in which a superconducting coil is formed by winding a compound superconducting wire or a superconducting cable formed by twisting this compound superconducting wire after being subjected to body-forming heat treatment (hereinafter referred to as “react treatment”) (React and Wind) method and the so-called Wind and React method in which a wire made of the wire material before the reacting process or a cable made of the wire material before the reacting process is wound and then subjected to the reacting process. is there.

Since the wind-and-react method does not process the compound superconducting wire after the compound superconducting wire is formed, the manufacturing method is taken to avoid distortion associated with this processing and to prevent deterioration of superconducting properties such as critical current. It is. When using the wind-and-react method, in order to avoid introduction of distortion caused by processing such as winding into the compound superconducting wire, the superconducting compound raw material in an unreacted state is wound in a coil shape in advance. in by reacting the Nb 3 _Sn is subjected to react processing, and generates an Nb 3 _Sn coil shape.

However, the wind-and-react method is not applied to the production of large magnets such as a high-field accelerator die ball magnet and a high-field large-diameter magnet, and the react-and-wind method is generally used. This is because the reacting process for generating Nb ₃ Sn needs to be performed in a furnace in a vacuum or an inert gas atmosphere at a predetermined temperature of 600 ° C. or higher. This is because the reacting process cannot be performed after the magnet is formed due to restrictions.

On the other hand, the greatest advantage of manufacturing a superconducting coil by the react-and-wind method is that a large heat treatment furnace for heat-treating the coil is not required, and the cost can be reduced by saving equipment costs. Until now, various attempts have been made to obtain a superconducting coil having high characteristics by using the react and wind method. For example, Patent Document 1 and Patent Document 2 disclose a compound-based superconducting coil and a method for manufacturing the same based on a react and wind method.
JP 2004-063128 A JP 2001-126554 A

Specifically, in Patent Document 1, after adding bending strain to a compound superconducting wire exhibiting strain dependence subjected to a reaction treatment, the bending strain is removed to improve the mechanical characteristics and the stress characteristics of critical current values. It is disclosed.

Further, Patent Document 2 discloses that a compound superconducting wire in which a compound superconducting phase is formed and a compound superconducting wire coated with enamel is bent a plurality of times at least 50 times the minimum cross-sectional width of the compound superconducting bare wire. It has been shown that degradation of superconducting properties can be remarkably suppressed by enamel coating under the condition of performing at a radius and maintaining a tension of 70 MPa or less.
As described above, various attempts as described above have been made, and as a result, it has been possible to achieve a certain degree of deterioration of critical current characteristics due to strain stress of compound superconducting wires and improvement of strain resistance characteristics.

  However, since the superconducting properties of the compound superconducting wire are deteriorated when the superconductor is subjected to strain, even if the superconducting coil is manufactured by the react-and-wind method described in Patent Document 2, the twisted wire processing and winding are performed. Addition of strain exceeding 0.4% due to wire processing causes a decrease in superconducting characteristics such as critical current, resulting in a problem in that various characteristics of the superconducting coil also deteriorate.

  An object of the present invention is to provide a superconducting coil composed of a compound superconducting wire with reduced internal strain and capable of improving the superconducting characteristics such as strain resistance and critical current value, and a method for manufacturing the same. Is.

  The present invention according to claim 1 is a superconducting coil formed by winding a compound superconducting wire that has been heat-treated for superconductivity generation, wherein the compound superconducting wire has a compound superconductor at least partially in its cross section. In addition, the present invention is a superconducting coil characterized in that after a predetermined compound superconductor generation heat treatment is performed, a double bending process is applied to apply bending strain from both the positive and negative directions to relieve internal strain of the compound superconducting wire. .

  The present invention according to claim 2 is characterized in that the double swing bending process is a single double swing bending process in which bending strain is applied once in both the forward and reverse directions. 2. The superconducting coil according to claim 1, wherein bending strain is applied from both the positive and negative directions within a range of 0.5% to 1.0%.

  According to a third aspect of the present invention, in the superconducting coil according to the second aspect, the single double bending process is repeated 5 to 20 times.

The present invention according to claim 4 is the superconducting coil according to any one of claims 1 to 3, wherein the compound superconductor is made of Nb ₃ Sn or Nb ₃ Al.

The present invention according to claim 5 is characterized in that the compound superconducting wire is provided with a reinforcing material made of any one of conductive materials of CuNb, CuAl ₂ O ₃ , CuNbTi and Ta. The superconducting coil according to any one of claims 1 to 4.

  The present invention according to claim 6 is the superconducting coil according to any one of claims 1 to 5, wherein the compound superconducting wire is provided with a stabilizing material.

  The present invention according to claim 7 comprises a superconducting cable formed by twisting a plurality of compound superconducting wires, or a superconducting cable formed by twisting and then forming. 6. The superconducting coil according to any one of 6 above.

  The present invention according to claim 8 is a method of manufacturing a superconducting coil by winding a compound superconducting wire subjected to heat treatment for generating a compound superconductor to form a superconducting coil, wherein the compound superconducting wire is subjected to bending strain from both positive and negative directions. A method of manufacturing a superconducting coil, comprising a double bending process.

  The present invention according to claim 9 is a method of manufacturing a superconducting coil by winding a compound superconducting wire subjected to heat treatment for generating a compound superconductor to form a superconducting coil, wherein the compound superconducting wire imparts bending strain from both forward and reverse directions. A method of manufacturing a superconducting coil, characterized in that the compound superconducting wire is manufactured.

The superconducting coil composed of a compound superconducting wire in which bending strain is imparted from both the positive and negative directions to the reacting compound superconducting wire according to the present invention, and the manufacturing method thereof, because the internal residual strain of the compound superconducting wire is relaxed and work hardening occurs. In addition, it exhibits excellent effects in superconducting characteristics such as stress resistance characteristics and critical current values.
Furthermore, the superconducting coil according to the present invention is formed by winding using a reacted compound superconducting wire. That is, by applying the react and wind method, a large heat treatment facility is not required, leading to a reduction in manufacturing cost and a high economic effect. In addition, it becomes possible to manufacture a large coil that cannot be manufactured due to dimensional constraints of the heat treatment furnace so far, and the industrial utility value is high.

Hereinafter, a superconducting coil and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.
First, the compound superconducting wire or the compound superconducting cable used in the superconducting coil according to the present invention is subjected to a double bending process by a method as shown in FIGS. This double-bending is a processing method for improving the strain resistance of the compound superconducting wire by subjecting the compound superconducting wire that has been subjected to the react treatment to at least one bending strain from both the front and back directions.

1 to 2 show examples of the double bending method.
1 is a reacted compound superconducting wire, 2 is a pass line for imparting bending strain, 2a is a bending strain imparting pulley constituting the pass line, 2b is a side view of the bending strain imparting pulley 2a, and 3 is a reacted compound A winding coil around which a superconducting wire is wound, 4 is a winding coil wound around a compound superconducting wire to which bending strain is applied, and 5 is a feed pulley for the compound superconducting wire.
The compound superconducting wire 1 or the compound superconducting cable unwound from the unwinding coil 3 is guided to a pass line 2 for applying a bending strain through a feed pulley 5 and is wound after receiving a predetermined bending strain amount and the number of bending times. The coil 5 is wound up. Next, it is wound around the superconducting coil in a winding process.

  In the double swing bending method shown in FIG. 1, a predetermined number of bending strain imparting pulleys 2a are arranged on the traveling direction of the compound superconducting wire 1, so that the compound superconducting wire 1 is bent in the same direction from the top and bottom in the traveling direction. Strain is imparted, and the bending strain imparting pulley 2a used at this time has a single groove in which the compound superconducting wire travels.

  In the double swing bending process shown in FIG. 2, the bending strain imparting pulley 2a is arranged so that the central axis thereof is perpendicular to the traveling direction of the compound superconducting wire 1 so that a predetermined bending strain characteristic can be obtained. The compound superconducting wire has a configuration in which a predetermined number is arranged, and bending strain is imparted from the slightly upside down direction. The bending strain imparting pulley 2a used at this time has a structure having a plurality of grooves in which the compound superconducting wire travels.

  FIG. 3 shows another embodiment of the double bending method. 6 is a cleaning device that removes oil and fat from the surface of the compound superconducting wire, and 7 is an insulating construction device that coats the compound superconducting wire with an insulating layer. The insulating layer is passed through the insulating construction device 7 a plurality of times. At the same time, a configuration in which a predetermined bending strain is applied to the compound superconducting wire by the bending strain adding pulley 20 without using a dedicated bus line for applying the bending strain as shown in FIGS. In the step of applying the insulating coating layer to the reacted compound superconducting wire, the double bending process can be performed by performing the double bending process one or more times.

As another swing bending method, as shown in FIG. 4, a bending strain composed of a bending strain imparting pulley 21 a is applied to an intermediate portion of a process of winding the compound superconducting wire 1 to produce the superconducting coil 8. Bending distortion can be imparted by arranging the pass line 21 and imparting bending distortion due to the double bending process to the reacted compound superconducting wire 1.
Furthermore, it is also possible to prepare a pass line so as to return the twist after adding twist to the compound superconducting wire at the time of the double bending process.

  As a condition of the above-described double bending process, when the applied bending strain is applied between 0.1 and 1.0%, the critical current is greatly improved, preferably 0.5 to 0.8%, In particular, it is preferable to apply a bending strain of about 0.8%, and the number of times of application is preferably 1 to 20 times.

  Next, as shown in FIG. 4, a superconducting coil having excellent superconducting characteristics is obtained by winding the compound superconducting wire or the compound superconducting cable subjected to the above-mentioned double bending process into a predetermined coil shape.

As the compound superconducting wire, a bronze CuNb reinforced Nb ₃ Sn compound superconducting wire (hereinafter abbreviated as compound superconducting wire) was used. The specifications are shown in Table 1. This compound superconducting wire may be one in which a reinforcing material such as CuNbTi, CuAl ₂ O ₃ or Ta is arranged in a part of its cross section, or may contain only a stabilizing metal (Cu) without including the reinforcing material. Furthermore, the manufacturing process may be a tube method other than the bronze method, an internal diffusion method, a jelly roll method, or a powder-in-tube method.

  The compound superconducting wire described in Table 1 is wound around a stainless steel bobbin (body diameter φ440 mm, winding width 200 mm) together with a glass tape (width 5 mm, thickness 50 μm), and this bobbin is placed in a vacuum furnace to react. Was given. The heat treatment condition was 670 ° C. × 96 hours. The heat treatment conditions may be any conditions other than the above as long as the compound superconductor is generated.

Next, while pulling out the compound superconducting wire from the stainless steel bobbin, the glass tape is removed and a polyimide tape (width 5 mm, thickness 50 μm) is further wound with a half wrap to form an insulating layer having a body diameter φ450 mm, width It was wound up on a 300 mm supply drum. In addition to this, the insulating layer may be coated with a resin such as formal or neomarl.
The insulated drum superconducting wire supply drum was set on the coil winding pass line shown in FIG. Ten pulleys having a diameter of 125 mm were arranged on the pass line, and a bending strain of about 0.8% was applied to the pulley through a compound superconducting wire. Therefore, the double bending was 5 times.
The compound superconducting wire provided with the double bending was wound around a bobbin, and a wire was wound while applying an epoxy resin to form a superconducting coil. The wire tension during winding was 31 to 37 MPa. Table 2 shows the specifications of this superconducting coil.

  In order to measure the characteristics of this superconducting coil, the superconducting coil was immersed in liquid helium and excited with a 10T magnetic field applied from the outside, and the electromagnetic force received by the superconducting wire in the coil winding was compressed. It was possible to energize up to 350A in the energizing direction. Further, the electromagnetic force can be energized up to 270 A in the energizing direction in the hoop direction opposite to the compression direction, and the hoop force at this time was 330 MPa.

Thus, the current value that can be energized by excitation in the compression direction has increased significantly due to the effect of the pre-bending strain. Further, the limit of the use range of the CuNb-reinforced Nb ₃ Sn compound superconducting wire so far is 200 to 300 MPa even in the hoop direction, but the superconducting coil using the superconducting wire to which pre-bending strain is applied can be improved to 330 MPa. did it.

It is process drawing explaining one aspect of the prior bending distortion provision method to a compound superconducting wire. It is process drawing explaining the other aspect of the pre-bending distortion provision method to a compound superconducting wire. It is process drawing explaining the prior bending distortion provision method in an insulating layer coating process. It is process drawing of a superconducting coil winding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reacted compound superconducting wire 2 Pass line for imparting bending strain 2a Bending strain imparting pulley 2b Side surface of bending strain imparting pulley 3 Unwinding coil 4 Winding coil 5 Feeding pulley 6 Cleaning device 7 Insulating construction device 8 Superconducting coil 20 Bending strain imparting pulley 21 Pass line for imparting bending strain 21a Bending strain imparting pulley

Claims (9)

A superconducting coil formed by winding a superconducting heat-treated compound superconducting wire, wherein the compound superconducting wire has a compound superconductor at least in a part of its cross section, and a predetermined compound superconductor generating heat treatment A superconducting coil is characterized in that, after being applied, a double bending process is applied to apply bending strain from both the positive and negative directions to relieve internal strain of the compound superconducting wire. In the single swing bending process, the double swing bending process is a single double swing bending process in which bending strain is applied at least once in both the forward and reverse directions. The superconducting coil according to claim 1, wherein bending strain is applied from both the positive and negative directions within a range of%. The superconducting coil according to claim 2, wherein the single swing bending process is repeated 5 to 20 times. The superconducting coil according to claim 1, wherein the compound superconductor is made of Nb ₃ Sn or Nb ₃ Al. The compound superconducting wire is provided with a reinforcing material made of any one of conductive materials of CuNb, CuAl ₂ O ₃ , CuNbTi, and Ta. The superconducting coil according to item. The superconducting coil according to any one of claims 1 to 5, wherein the compound superconducting wire is provided with a stabilizing material. The superconducting cable formed by twisting a plurality of the compound superconducting wires, or a superconducting cable formed by twisting and then forming the superconducting cable according to any one of claims 1 to 6. Superconducting coil. A superconducting coil manufacturing method for forming a superconducting coil by winding a compound superconducting wire that has been heat-treated to form a compound superconductor, comprising a double bending process for imparting bending strain to the compound superconducting wire from both directions A method of manufacturing a superconducting coil, comprising: A method for producing a superconducting coil by winding a compound superconducting wire that has been heat-treated to form a compound superconducting coil, wherein the compound superconducting wire is a compound superconducting wire to which bending strain is imparted from both the positive and negative directions. A method of manufacturing a superconducting coil, which is characterized.

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